An empty frame sits where Rembrandt’s “The Storm on the Sea of Galilee” hung until it was stolen in 1990. (Josh Reynolds / AP)

On March 18, 1990, the Isabella Stewart Gardner Museum in Boston was robbed of 13 works of art. As of March 2015, the stagnant investigation was ongoing. Over 16 years and many red herrings later, the FBI has found an encouraging lead.

On March 18, 2013 — 23 years after the exact day of the heist — the FBI announced that they had information on the crime. The art had been transferred to Philadelphia by way of Connecticut, but the FBI was still unable to locate it. Federal investigators announced they knew the identities of the perpetrators, but did not provide any further information.

Authorities arrived May 1, 2016 at the Manchester, Connecticut home of Robert Gentile, 79, who is believed to be affiliated with the Philadelphia Mafia, with a search warrant for the $500 million worth of lost art. Gentile failed a lie detector test in 2012 when asked about the whereabouts of the art; that is what gave detectives a reason to believe he may have been involved in committing the crime.

Gentile was not present at the house during the search. In 2015, he was convicted of various gun and drug related charges and is currently serving a two-and-a-half year sentence in federal prison. In the past, Gentile vehemently denied any connection to the robbery.

“He laughed and he couldn’t believe they were there, that they were at his house again,” said Rome McGuigan, Gentile’s lawyer, in an interview with ABC News, “He said, this is a quote, ‘They ain’t gonna find nuttin.’”

According to the Gardner Museum website, the stolen artworks are as follows: Rembrandt’s “Storm on the Sea of Galilee” (1633), “A Lady and Gentleman in Black” (1633) and “Self Portrait” (1634); Jan Vermeer’s “The Concert” (1658 – 1660); Govaert Flinck’s “Landscape with an Obelisk” (1638); five Edgar Degas works on paper; and Edouard Manet’s “Chez Tortoni “(1878 – 1880). Also stolen were a Chinese vase and a finial from the top of a Napoleonic silk flag.

The FBI is offering a $5 million reward for the return of the artwork in good condition. There is no word yet on whether investigators found anything from their search.